132 



THE VOYAGE OF H.M.S. CHALLENGER. 



the eighth, row of suckers the two ventral series are continued of the normal size, but the 

 two dorsal are each represented by five minute suckers, gradually diminishing to the 

 middle one and then increasing again ; beyond this the arm exhibits no peculiarities. 

 The umhrella is widest between the two lateral arms, where it extends as far 

 as the sixth row of suckers. The buccal mcnibrane bears the usual seven distinct 

 points in the male, whilst in the female the ventral pair are lost in the thick swollen 

 spermatic pad (fig. 15), which is subdivided by four or five deep grooves into as many 

 transverse ridges. The outer lip> is thin; the inner bears about half a dozen rows of 

 distinct hemispheroidal papillse. 



Tlie Tentacles are about as long as the mantle ; the stem is indistinctly three- 

 sided ; the club is long and wide, and bears eight series of minute ec[ual suckers ; there 

 is a protective membrane on either side and a broad Jin on the dorso -internal aspect. 

 The homy ring is small and has a smooth margin. 



The Surface is smooth. 



Tlie Colour is a dull grey dorsally, pale yellowish below. 



Tlie Jaws are shown in figs. 20, 21. 



Tlie Shell (figs. 22—24) is broad, subelliptical in outline, the anterior extremity 

 bounded by two straight lines, which form obtuse rounded-ofi" angles with each other 

 and the sides of the shell ; the posterior is rounded gradually off. The dorsal surface 

 has a faint ridge passing to each of the three angles just mentioned, and is covered 

 with curved rows of tubercles parallel to the anterior margin. The ventral surface is 

 but little elevated ; the last loculus has an index of 34, and is bounded behind by a 

 broadly open curve with three or four irregular sinuations in it. The striated area is 

 hollowed posteriorly and, is marked by grooves corresponding to the sinuations just 

 mentioned. The inner cone arises about halfway along the striated area, curves evenly 

 outwards, and then rises into a distinct ridge, forming a wall separate from the margin 

 of the shell ; its ventral surface is marked by a number of strise pointing in the 

 direction of the spine, which is of medium length and strength, and curved gently 

 upwards. 



Dimensions 



1 









Length, total, 



. 102 



End of body to mantle-margin, 









72 



End of tody to eye, 









66 



Breadth of tody, .... 









40 



Breadth of head, .... 









33 



Eye to edge of umbrella, . 









15 



Breadth of fin, . 









11 



Diameter of largest sucker on sessile arm. 









1 



Length of shell, .... 









72 



Breadth of shell, .... 









31 



1 Taken from one of the female speci 



mens fro 



m Static 



a 188. 





